Such support jacks are usually found in paired arrangement on the bottom of semitrailers. Usually they comprise an outer tube which can be mounted stationary on the trailer and a second inner tube, telescoping in the former tube, and having a base plate located at its end. To uncouple the trailer, the support jacks are extended, so that they support the trailer in its front region and allow the tractor to drive off from underneath the trailer. In presently used pneumatic cushioned trailers, a sinking of the back region of the trailer can occur during lengthy standstill, caused by a loss of pressure in the pneumatic bellows of the trailer. Due to the sinking of the trailer, shear forces also act in the longitudinal axis of the support jacks, resting on the ground with their support surfaces frictionally engaged, and therefore exposed to a substantial bending and buckling stress.
To counteract this effect, efforts had already been undertaken in the past to arrange a wheel segment at the lower region of the support jack, which equalizes the shear forces occurring by a rolling against the base plate located underneath.
A known wheel segment is described in DE 40 03 414 A1, consisting of several individual components that are welded together. Such a fabrication is extremely costly, since the side walls have to first be oriented exactly relative to each other before being welded to the rolling surface. Then additional reinforcing plates are welded individually by hand to the side walls and the cross arms running between them.